Diaphragm pumps are well known in the art. Characteristic of such pumps is a housing separated into first and second chambers by a diaphragm. In some instances the diaphragm comprises a rigid central disk portion and a flexible annular portion about the disk. The diaphragm is attached to the housing in a manner to seal the two chambers. Electromagnetic means causes cyclical displacement of the diaphragm alternately expanding and reducing the volume of the chambers reciprocally in a push-pull mode of operation. Each chamber is equiped with an inlet and outlet conduit including check valves operative to admit and eject fluids in the appropriate phases of operation. Displacement of the diaphragm in a first direction increases the volume of one of the chambers in a manner to draw fluid into the chamber through an inlet valve. Displacement of the diaphragm in the opposite direction thereafter reduces the volume of that same chamber, and causes fluid therein to be expelled through an outlet valve.
One problem with such arrangements is that the operation of a diaphragm pump usually requires a second gaseous or liquid medium, other than the gas or liquid being pumped, on one side of the diaphragm. This second gaseous or liquid medium needs venting. Such a requirement for venting precludes the use of a sealed exterior surface of such a pump in submersed or otherwise hostile environments as would occur if used in space or as a heart replacement in an animal or human.
A second problem with such arrangements is that any diaphragm material has a finite permeability. This permeability permits some small portion of the fluid on each side of the diaphragm to reach the other side of the diaphragm, resulting in loss of a small part of the fluid being pumped, and contamination of the fluid being pumped.
A third problem with such arrangements is that any material being used as a diaphragm will crack or rupture when subjected to sufficient pressure and flexing. When such a crack or rupture occurs the gas or fluid on each side of the diaphragm is contaminated by mixing with the gas or fluid on the other side.